As is well known, numerous articles of manufacture are molded from various elastomeric rubber and plastic materials. In such molding processes, there oftentimes exists residual material or flash formed on the articles at their part lines, i.e. the area adjacent the interfacing mold surfaces. Such residual flash is not only aesthetically objectionable, but additionally functionally objectionable, and therefore must be removed, i.e. deflashed, from the article prior to use of the same.
Heretofore, it has been customary practice to deflash such articles by hand, requiring the severing of the flash from the article by way of a knife or razor. Such hand deflashing process is costly due to the substantial labor time required to be expended to properly trim the particular article. Furthermore, in some instances it is difficult if not impossible to accomplish a satisfactory deflashing operation as where a particular molded article configuration prohibits manual access to the flash. As a articles is oftentimes substantially increased above actual molding production costs due to the high costs involved with deflashing procedures.
As a consequence of such high deflashing costs, in recent years, cryogenic deflashing apparatus have been introduced into the marketplace which in many instances have eliminated the requirement of costly hand trimming of residual flash from molded rubber and/or plastic manufactured articles. Basically such prior art cryogenic deflashing apparatus comprise a chamber maintained at an extremely low temperature by use of a cryogen gas such as nitrogen into which is introduced a high velocity stream of blasting media typically comprising plastic pellitized shot. The molded articles to be deflashed, such as O-rings, grommets, bushings, and the like, are emplaced within the deflashing chamber wherein, due to the relatively greater thickness of the molded article compared to the residual flash thereon, only the residual flash becomes embrittled in the low temperature environment. In its embrittled state, the residual flash is rapidly separated from or broken off of the molded article by the impact of the high velocity blasting media stream. By controlling the exposure duration of the molded articles within the cryogenic environment, as well as the velocity and dispersion of the deflashing media thereagainst, it has been found that satisfactory article deflashing may be accomplished, typically at a substantial reduction over hand deflashing operations.
Although such prior art cryogenic deflashing apparatus have generally proven to be superior over hand deflashing operations, they have possessed inherent deficiencies which have detracted from their widespread use in the trade. Foremost of these deficiencies has been the relatively large size and cost heretofore associated with such apparatus. In this regard, to insure continuous transport of media to the throwing wheel and thereby insure proper deflashing operations, it has been customary for prior art cryogenic deflashing apparatus to include complicated feed hopper/transport auger mechanisms to convey the blasting media to the throwing wheel. The use of such feed hopper/auger transport mechanisms has necessarily increased the overall size and cost of the apparatus and has mandated that large amounts of deflashing media be maintained within the apparatus, i.e. sufficient amounts to fill the hopper and auger conduit. Further, since the media accumulates spent flash removed in the deflashing process, the requirement of large amounts of media in such deflashing apparatus has additionally required the use of expensive media/flash separation units to be incorporated into the apparatus or alternatively the replacement of large amounts of blasting media during prolonged operation. Additionally, the use of such feed hopper/auger/separating systems in the prior art have proven to be prone to mechanical failure, thereby increasing maintenance costs for the apparatus.
In addition, conventional cryogenic deflashing apparatus have typically proven defective in preventing spillover, i.e. loss, of molded articles within the deflashing chamber during the deflashing operation. Such spillover problems arise primarily upon impact of the molded articles with the blasting media, whereby the molded articles are thrown out of the article basket and enter into the blasting media transport mechanism. As such it has not been uncommon for a relatively large percentage of molded articles to be lost during the cryogenic deflashing process, thereby reducing overall cost effectiveness of the same.
Further, due to the cost and size limitations of the prior art, most cryogenic deflashing apparatus have required dedicated production space to be provided for the apparatus as well as have required permanent hardwire electrical service to the same. As such, the prior art cryogenic deflashing apparatus have proven to be immobile and non-transportable to a particular job location to increase overall production efficiency.